211 lines
6.3 KiB
Java
211 lines
6.3 KiB
Java
/* StringReader.java -- permits a String to be read as a character input stream
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Copyright (C) 1998, 1999, 2000 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.io;
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct
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*/
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/**
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* This class permits a <code>String</code> to be read as a character
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* input stream.
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* <p>
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* The mark/reset functionality in this class behaves differently than
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* normal. If no mark has been set, then calling the <code>reset()</code>
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* method rewinds the read pointer to the beginning of the <code>String</code>.
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*
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* @version 0.0
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Warren Levy <warrenl@cygnus.com>
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* @date October 19, 1998.
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*/
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public class StringReader extends Reader
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{
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/* A String provided by the creator of the stream. */
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private String buf;
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/* Position of the next char in buf to be read. */
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private int pos;
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/* The currently marked position in the stream. */
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private int markedPos;
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/* The index in buf one greater than the last valid character. */
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private int count;
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/**
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* Create a new <code>StringReader</code> that will read chars from the
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* passed in <code>String</code>. This stream will read from the beginning to the
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* end of the <code>String</code>.
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*
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* @param s The <code>String</code> this stream will read from.
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*/
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public StringReader(String buffer)
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{
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super();
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buf = buffer;
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count = buffer.length();
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markedPos = pos = 0;
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}
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public void close()
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{
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synchronized (lock)
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{
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buf = null;
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}
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}
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public void mark(int readAheadLimit) throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("Stream closed");
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// readAheadLimit is ignored per Java Class Lib. book, p. 1692.
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markedPos = pos;
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}
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}
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public boolean markSupported()
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{
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return true;
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}
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public int read() throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("Stream closed");
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if (pos < count)
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return ((int) buf.charAt(pos++)) & 0xFFFF;
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return -1;
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}
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}
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public int read(char[] b, int off, int len) throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("Stream closed");
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/* Don't need to check pos value, arraycopy will check it. */
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if (off < 0 || len < 0 || off + len > b.length)
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throw new ArrayIndexOutOfBoundsException();
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if (pos >= count)
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return -1;
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int lastChar = Math.min(count, pos + len);
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buf.getChars(pos, lastChar, b, off);
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int numChars = lastChar - pos;
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pos = lastChar;
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return numChars;
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}
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}
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/**
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* This method determines if the stream is ready to be read. This class
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* is always ready to read and so always returns <code>true</code>, unless
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* close() has previously been called in which case an IOException is
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* thrown.
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*
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* @return <code>true</code> to indicate that this object is ready to be read.
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* @exception IOException If the stream is closed.
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*/
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public boolean ready() throws IOException
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{
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if (buf == null)
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throw new IOException("Stream closed");
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return true;
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}
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/**
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* Sets the read position in the stream to the previously
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* marked position or to 0 (i.e., the beginning of the stream) if the mark
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* has not already been set.
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*/
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public void reset() throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("Stream closed");
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pos = markedPos;
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}
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}
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/**
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* This method attempts to skip the requested number of chars in the
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* input stream. It does this by advancing the <code>pos</code> value by
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* the specified number of chars. It this would exceed the length of the
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* buffer, then only enough chars are skipped to position the stream at
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* the end of the buffer. The actual number of chars skipped is returned.
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*
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* @param num_chars The requested number of chars to skip
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*
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* @return The actual number of chars skipped.
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*/
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public long skip(long n) throws IOException
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{
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synchronized (lock)
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{
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if (buf == null)
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throw new IOException("Stream closed");
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// Even though the var numChars is a long, in reality it can never
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// be larger than an int since the result of subtracting 2 positive
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// ints will always fit in an int. Since we have to return a long
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// anyway, numChars might as well just be a long.
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long numChars = Math.min((long) (count - pos), n < 0 ? 0L : n);
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pos += numChars;
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return numChars;
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}
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}
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}
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